Lots of indecision here!   It is going to be very cold, still, so overheating is a bad idea. For your warm up, please try to start skiing on time, keep it simple and just ski steadily for the half hour, but avoid heavy  breathing or sweating.  Include some skiing without poles,  and  3 or 4 short sprints that last up to 15 seconds each ( no longer!), preferably on an uphill, and then follow each sprint with a few minutes of that steady and easy skiing.  Don't forget to include lots of double poling too!

We may briefly review step double pole, and depending on conditions we will  work on some downhill or uphill skills (very vague!)   And finish with a group ski, with a twist.